Laryngitis

Acute laryngitis is commonly due to infection but there are rarer causes. The basic pathophysiology is inflammation of the mucosa lining the vocal folds and larynx. If infection is involved, white cells aggregate to remove infectious material from the area. Oedema of the laryngeal lining increases the amount of pressure required to produce sound, resulting in dysphonia or aphonia. Changes to the structure of the larynx may also result in a lower register of speech. Chronic laryngitis can be due to a variety of different causes, including reflux, allergy, trauma and autoimmune disease. Depending on the cause, there may be laryngeal spasm, hyperaemia, oedema, inflammation and various changes to the morphology of the laryngeal mucosal cells.


Trauma:
Trauma due to voice misuse -screaming, yelling, loud singing. Trauma due to excessive voice use -more common in certain professions such as teachers, actors and singers. Coughing. Penetrating or blunt external force. Habitual throat clearing.
Smoking. [5] Autoimmune disease -chronic laryngitis may be a feature of systemic disease in conditions such as rheumatoid arthritis, systemic lupus erythematosus, amyloidosis, pemphigoid. Sarcoidosis. Medication such as: [6] Angiotensin-converting enzyme (ACE) inhibitors by causing cough. Inhaled steroids by promoting fungal infection. Antihistamines, anticholinergics and diuretics -all by resulting in drying of the mucosa. Bisphosphonates by causing a chemical laryngitis. Danazol and testosterone.

Chronic laryngitis
By definition, any patient with symptoms of acute laryngitis persisting for longer than three weeks should be deemed to have chronic laryngitis. In such patients, the following additional information should be sought: Personal history: Duration of symptoms, any relieving or aggravating factors. Symptoms suggestive of ill health -lung cancer, thyroid disease. Occupational history, especially exposure to irritant substances or temperature change. Voice abuse. Symptoms suggestive of gastro-oesophageal reflux disease (GORD) -eg, heartburn, chest pain, otalgia, cough, wheezing, globus, throat clearing. History of asthma -this can sometimes be confused with vocal cord dysfunction; history is of throat rather than chest discomfort, often with additional atypical symptoms (voice difficulty, laryngeal stridor, wheeze worse in inspiration). History of allergy. Immunocompromised patients -consider candidal involvement.
Medication history: Medications causing local drying or mucosal injury, as above Drugs increasing the tendency to develop GORD by decreasing the tone of the lower oesophageal sphinctercalcium-channel blockers, nitrates, beta-blockers, progesterone. Immunosuppressant therapy -consider candida. Inhalation treatments -thermal baths.
Surgical history: History of intubation -recurrent laryngeal damage, particularly likely in thoracic and abdominal surgery. Surgery leading to anatomical alterations predisposing to GORD (again, thoracic and abdominal).
Ingestion of caustic substances.
Travel history (for the possibility of parasitical infections).

Examination
Unless the clinician is experienced in the technique of indirect laryngoscopy (indirect examination of the larynx, using a laryngeal mirror), examination in the limited context of primary care is generally unhelpful, other than to exclude other conditions such as pharyngitis.
Patients whose symptoms persist for more than three weeks should have indirect laryngoscopy.
Examination may give some indication to the underlying cause. Signs to look out for include: Masses in the neck. Lymphadenopathy.
Signs of systemic autoimmune disease -rashes, joint deformity. Signs of possible bacterial infection such as persistent fever, purulent sputum, signs in the chest. Signs of epiglottitis. Stridor and signs of impending airway obstruction. Signs of specific causative organisms, such as oral thrush, or herpetic vesicles.
Red flags [1] All those with symptoms of a hoarse voice/change to the voice for three weeks should be referred for laryngoscopy to exclude sinister laryngeal pathology.

Assessment of airway patency is vital, and stridor would prompt emergency referral.
Other factors which should prompt urgent referral include:

Differential diagnosis
See also the separate article Hoarseness.

Chronic laryngitis
Nodules, polyps and cysts affecting the vocal cords. Malignancy -laryngeal cancer, lymphoma, thyroid cancer, lung cancer. Chondronecrosis of the larynx. Glottic or subglottic stenosis. Iatrogenic vocal cord scar. Medication side effect -eg, antipsychotics can cause laryngeal dystonia, warfarin increases the risk of haematoma, drying effect of anticholinergics, etc. Vascular lesions of the vocal cords.

Acute laryngitis
Investigations are rarely helpful in primary care. A swab for microbiological analysis may be contributory if excessive exudate is present. Clinicians with the skill to perform indirect laryngoscopy will typically find redness and small dilated vasculature on the inflamed vocal folds.

Chronic laryngitis
Investigations will depend on the clinical picture. Most will be done in secondary care, as referral for laryngoscopy will have been made.

Laboratory tests:
FBC with differential to exclude infection. Sputum culture for bacteria, fungi and viruses. Laryngeal mucosal swab for microbiological analysis. Serology for autoimmune markers.
Tests for syphilis and tuberculosis if clinically indicated. [8] Endoscopic visualisation: Indirect or direct laryngoscopy. Videostroboscopy -unit consists of a stroboscopic unit (light source and microphone), a video camera, an endoscope and a video recorder. Useful in diagnosing vocal cysts, polyps and nodules. [9] Imaging: Lateral X-ray of the neck -may show supraglottic or retropharyngeal swelling, or soft tissue density in subglottic airway. CXR. CT and MRI scanning may be appropriate where pathology outside the larynx is suspected. Barium swallow study, double-contrast upper gastrointestinal series and manometry -may be considered to exclude GORD. The best method of diagnosis for reflux in this situation remains controversial and is currently a target for research studies.
Management [1] Acute laryngitis Most cases are mild and self-limiting. "Vocal hygiene" describes a group of self-help measures including: Resting the voice. Avoidance of smoking and alcohol (both irritants, and alcohol causes dehydration). Humidification -promotes moisture of the upper airway, helping to clear secretions and exudate. Hydration -chewing sugar-free gum and/or increasing fluid intake (250 ml per hour awake). Reducing caffeine (as it causes dehydration, reflux and snoring).
Antibiotics have a limited place in the initial management of acute laryngitis. A Cochrane review found no significant difference in clinical outcome in adult patients given penicillin V or erythromycin compared with placebo. [10] Antibiotics may be helpful in patients who have persistent fever (for more than 48 hours), purulent sputum, associated distant disease or other problems such as immune system deficiency.

Chronic laryngitis
Voice hygiene methods as described above.
Voice therapy -exercises with the help of a speech therapist may be of benefit in some cases. This modifies voice use to reduce trauma to the larynx. Treat the underlying condition where possible -eg, GORD may need appropriate lifestyle advice and a trial of proton pump inhibitors. (There should be an awareness that a significant number do not respond and of the side-effects and risks of longterm treatment.) Laparoscopic reflux surgery (laparoscopic fundoplication) may have a role. The best way to diagnose and treat reflux disease in this situation remains unclear. [11] Complications Acute laryngitis -complications are rare, as the disease is usually self-limiting. Damage to the vocal cords is possible in patients who try to overcompensate for the dysphonia. Chronic laryngitis -the main complications are voice loss, obstruction of the airways and chronic cough. Laryngeal stenosis may develop occasionally. Rarely, in severe infections such as those with herpes viruses, laryngeal erosion and necrosis may occur. [1] Prognosis In acute laryngitis, the prognosis is usually excellent. With chronic laryngitis the prognosis depends on the underlying condition.

Prevention
There are no particular preventative measures for acute laryngitis, although avoidance of irritant factors such as cigarette smoke may be helpful. In chronic laryngitis: Irritant factors should be avoided -especially active or passive smoking. Patients on inhaled steroids should be advised regarding appropriate use -eg, dose reduction, twice-daily dosing, mouth rinsing and use of spacers. Lifestyle advice should be given to patients at risk of GORD.
Further reading & references